白酒基酒中醛类物质的傅里叶变换近红外光谱检测

乙醛和乙缩醛对白酒的香气起均衡协调的作用,对白酒的风格和品质有重大影响。本实验研究白酒基酒中乙醛、乙缩醛的快速检测方法,经过分析白酒基酒样品的近红外光谱图,并对其进行不同的预处理。结果表明:白酒基酒中的乙醛、乙缩醛对傅里叶变换近红外光谱有特异吸收,最佳预处理方法与最优波段分别为:一阶导数+矢量归一化、一阶导数+多元散射校正预处理光谱,谱区选择7 501.7~7 102.0 cm-1和6 101.7~5 446.0 cm~(-1)(乙醛)、6 101.7~5 449.8 cm~(-1)(乙缩醛)。乙醛和乙缩醛校正集样品的化学值与近红外的预测值的决定系数(R2)分别为0.963 4、0.942 9;校正标准偏差分别为0.50、0.83 mg/100 m L;进一步对乙醛、乙缩醛的模型进行验证和评价,乙醛和乙缩醛模型验证集的决定系数(R2)分别为0.975 0、0.918 6,预测标准偏差分别为0.80、1.0 mg/100 m L。结果表明乙醛和乙缩醛的快速检测模型效果很好,精密度较高、稳定性良好,能满足白酒生产中乙醛和乙缩醛的快速检测要求。

Determination of Aldehydes in Liquor Base Based on Fourier Transform Near-Infrared Spectroscopy

Acetaldehyde and acetal, aroma compounds important to the balance and harmony of liquor have a significant
impact on its flavor and quality. In order to accurately and quickly measure acetaldehyde and acetal in base liquor, calibration
models were established based on Fourier-transform near infrared (FT-NIR) spectroscopy with artificial neural network by
cross-validation after the spectra were analyzed. The results showed that the acetaldehyde and acetal in liquor base exhibited
a strong characteristic absorption in the near infrared (NIR) region. The best spectral pretreatment methods were found to be
first derivative + vector normalization (SNV) and first derivative + multivariate scatter correction (MSC). According to the
selected spectral ranges of 7 501.7–7 102.0, 6 101.7–5 446.0 cm-1 (for acetaldehyde) and 6 101.7–5 449.8 cm-1 (for acetal),
the internal cross validation method was adopted to establish a model. Through optimization of the model, the coefficients
of determination (R2) between chemically measured values and NIR predicted values in calibration set for acetaldehyde
and acetal were 0.963 4 and 0.942 9, respectively with internal cross-validation root mean square deviation of 0.50 and
0.83 mg/100 mL, respectively. The prediction model for acetaldehyde and acetal was validated. It was demonstrated
that the R2 values for acetaldehyde and acetal in validation set were 0.975 0 and 0.918 6, respectively with prediction
standard deviation of 0.80 and 1.0 mg/100 mL, respectively. The method has been applied to quick determination of the
concentrations of acetaldehyde and acetal with satisfactory results in the distilled spirit industry.